Method for operating a steering unit for a steer-by-wire ship&#39;s control system

ABSTRACT

A method of operating a steering unit for a steer-by-wire ship control system, comprising a steering wheel, a controller that is connected to the electronic controller of the steer-by-wire ship control system (ECU), a sensor for detecting the angular position of the steering wheel, and a device for generating mechanical resistance at the steering wheel. The mechanical resistance generated at the steering wheel, by the device for generating mechanical resistance at the steering wheel upon actuation of the steering wheel by an operator, depends on the speed of the engine or ship. The resistance is raised as the speed increases until a predetermined threshold is reached. If an auto-pilot device is activated, then the mechanical resistance has a constant value at every speed.

This application is a National Stage completion of PCT/EP2008/062898 filed Sep. 26, 2008, which claims priority from German patent application serail no. 10 2007 048 055.7 filed Oct. 5, 2007.

FIELD OF THE INVENTION

The present invention relates to a method for operating a steering unit for a steer-by-wire ship's control system comprising a helm (steering wheel), a controller that is connected to the electronic controller of the ship's control system (ECU), a sensor for detecting the angular position of the helm, and a device for generating mechanical resistance in the helm.

BACKGROUND OF THE INVENTION

In the state of the art, steer-by-wire systems are known which are also used in ship control technology. In systems of this kind, the steering commands are detected by a sensor and relayed via a control unit to an actuator, which implements the steering command. Advantageously, there is no mechanical connection between the helm and the rudder, or, as in the case of a motor vehicle, between the steering wheel and the wheels it controls.

A steer-by-wire ship's control system is known, for example, from U.S. Pat. No. 6,431,928 B1. In the known system, an electric motor is provided for pivoting the entire propeller drive unit via a mechanical energy transmission chain, wherein the electric engine is controlled by a control unit that is connected, on the one hand, to the steering device, in order to receive steering command information, and on the other hand, to the sensor that detects the steering position.

From U.S. Pat. No. 7,137,347 B2, a steering unit for a steer-by-wire ship's control system is known, which has a mechanically pivotable steering device, for example a helm, a sensor for detecting the rotation of the helm, and a stop-mechanism for blocking any further pivoting of the helm to starboard or to portside when the rudder of the vessel has reached a starboard or portside hardover position.

From EP 1770008 A2, a steer-by-wire ship's control system is known that comprises at least two steering units. Here, the rudder is operated by means of a hydraulically actuatable actuator by means of steering signals which are generated by the steering device that demands faster movement of the rudder. In the known system, the steering units each comprise a helm that is connected in each case to a controller, which is in turn connected to the control network.

Furthermore, it is provided that the steering devices, in the event of an actuation, or as the case may be a pivoting of the helm, depending on signals from a sensor for detecting the rudder position, produce a mechanical resistance by means of clutches, this resistance becoming greater, the closer the rudder moves to an end position. Once an end position has been reached, the mechanical resistance of the helm is set such that further pivoting in the same direction is not possible. This is made possible by a clutch which does not allow any pivoting of the helm in a completely closed state.

Furthermore, a control system for an outboard engine is known from U.S. Pat. No. 6,843,195 B2 in which the quotient of “realized steering angle/steering angle specified by the helm” decreases with rising speed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is based on the object of providing a method for operating a steering unit for a steer-by-wire ship's control system, the implementation of which will increase comfort and safety.

According to the invention, a method for operating a steering unit for a steer-by-wire ship's control system is disclosed, the method comprising a helm, a controller that is preferably connected by means of a CAN bus to the electronic controller of the ship's control system (ECU), a sensor for detecting the angular position of the helm (steering wheel), and a device for generating mechanical resistance in the helm, in the scope of which, in the event that no auto-pilot device is activated, the mechanical resistance generated at the helm upon actuation of the helm by the user depends on the speed, the resistance being increased with increasing speed up to a predefined threshold value. If an auto-pilot device is activated, the mechanical resistance has a constant (high) value at every speed. The design according to the invention increases the safety, because very rapid maneuvering at high speeds is largely avoided.

An advantageous refinement of the invention defines a speed, which preferably amounts to 10 kn, below which no mechanical resistance is generated by movement of the helm, wherein above this speed, the mechanical resistance generated at the helm by the device for generating mechanical resistance in the helm is increased, preferably in a linear manner, as a function of the speed, up to a predefined threshold value. For example, the predefined value can be 15 Nm.

According to a variant of the method presented here, a non-reset zone, a reset zone, and a boundary zone are defined around the current zero position of the helm, which is to say around the starting position before conducting a steering movement, for the eventuality that the steering unit has a device for resetting the helm, wherein if the angular position of the helm is within the non-reset zone during a steering actuation by the user, the helm is not reset to the current zero position of the helm, wherein if the angular position of the helm, after a steering actuation by the user, is within the reset zone, the helm is reset by the device for resetting the helm at a constant speed to the current zero position of the helm, or to a position within the non-reset zone.

According to the invention, the functionality of the device for resetting the helm can be performed by the device for generating a mechanical resistance at the helm, this is possible according to the design, for example, if the device for generating a mechanical resistance is configured as an electric motor. Both safety and comfort are increased by the pivotable range of the rudder the division into zones and zone-dependent control of the electric motor.

It is also proposed that if the angular position of the helm is within the boundary zone after a steering movement by the operator, the device for resetting the helm is operated in such a way that the helm cannot be moved farther in the direction of the steering movement, or can only be moved in the direction of the movement with considerable force (such force being greater than the force required to move the helm if the angular position thereof is within the reset zone), and is reset at a constant speed to a defined angular position within the reset zone, or to a position within the non-reset zone.

According to the invention, the non-reset zone is defined as the region between +X° and X° around the current zero position of the helm (which is to say the starting position before the steering movement is performed), wherein the reset zone is defined as the region between the ends of the non-reset zone and Y% of the maximum possible number of helm rotations in a clockwise and counterclockwise direction; the regions between Y% and 100% of the maximum possible number of helm rotations in a clockwise and anticlockwise direction are defined as the boundary zone, where X can be values between 1 and 135, and Y can be values between 45 and 95.

According to an advantageous refinement, it is proposed that if no auto-pilot device is activated, the mechanical resistance generated at the helm by the device for generating mechanical resistance at the helm in the reset zone and in the non-reset zone depends on the speed, wherein the resistance is raised with increasing speed until a predetermined threshold value is reached, wherein if an auto-pilot device is activated, the mechanical resistance has constant, predetermined, and preferably high value at every speed. In the boundary zone, the value of the mechanical resistance is either a constant maximum value, or the mechanical resistance is increased up to the maximum value, as a function of the number of revolutions still to go before the maximum possible number of helm revolutions is reached.

If no auto-pilot device is activated and the angular position of the helm is in the reset zone or the non-reset zone, according to an advantageous refinement a speed is defined, below which no mechanical resistance is generated by pivotal movement of the helm, wherein above that speed, a mechanical resistance is generated, which is increased, preferably in a linear manner, as a function of the speed, up to a predefined threshold value.

The method according to the invention can be used in steer-by-wire ship's control systems regardless of the type of steering actuator connected to the rudder.

For example, the actuator can be configured as a hydraulic or electromechanical actuator. The ECU processes the signals from the steering unit that is activated by the user or from an auto-pilot device and relays them to the steering actuator. The steering actuator is operated according to the input from the steering unit and the ECU with respect to the steering angle and the rotational speed of the rudder. If the auto-pilot device is activated, the rudder position is continuously updated by the steering unit controller. 

1-6. (canceled)
 7. A method of operating a steering unit for a steer-by-wire ship control system, in which the steering unit comprises a steering wheel, a controller that is connected to an electronic controller of a ship control system (ECU), a sensor for detecting the angular position of the steering wheel, and a device for generating mechanical resistance at the steering wheel, the method comprising the steps of: generating the mechanical resistance at the steering wheel by the device for generating mechanical resistance at the steering wheel upon actuation of the steering wheel by an operator depends on speed of the ship; raising the mechanical resistance at the steering wheel as the speed of the ship increases until a predetermined threshold value is reached; and if an auto-pilot device is activated, maintaining the mechanical resistance at a constant value for every speed.
 8. The method of operating a steering unit for a steer-by-wire ship control system according to claim 7, further comprising the steps of defining a speed, below which no mechanical resistance is generated by pivoting the steering wheel, and above this speed, the mechanical resistance generated by the device for generating mechanical resistance at the steering wheel is increased up to a predetermined threshold value as a function of the speed.
 9. A method of operating a steering unit for a steer-by-wire ship control system in which the steering unit comprises a steering wheel, a controller that is connected to an electronic control unit of a ship control system (ECU), a sensor for detecting the angular position of the steering wheel, and a device for generating mechanical resistance at the steering wheel, the method comprising the steps of: defining a non-reset zone, a reset zone, and a boundary zone in a range of angular positions of the steering wheel with respect to a current zero-position of the steering wheel (which is to say the starting position before performing a steering movement), if the steering unit has a device for resetting the steering wheel; if the angular position of the steering wheel, during a steering actuation by an operator, is within the non-reset zone, then delaying resetting the steering wheel to the current zero-position of the steering wheel; if the angular position of the steering wheel, after a steering actuation by the operator, is within the reset zone, then resetting the steering wheel with the device for resetting the steering wheel at a constant speed to either the current zero-position of the steering wheel, or a position in the non-reset zone; and if the angular position of the steering wheel, after a steering actuation by the operator, is within the boundary zone, then operating the device for resetting the steering wheel such that the steering wheel either cannot be moved further in a direction of the steering movement, or can only be moved in the direction of the steering movement with considerable force, and is reset at a constant speed to either a defined angular position within the reset zone or a defined position within the non-reset zone.
 10. The method of operating a steering unit for a steer-by-wire ship control system according to claim 9, further comprising the steps of: defining the non-reset zone as an angular region between +1° and 135° around the current zero-position of the steering wheel (which is to say the starting position before performing the steering movement); defining the reset zone as angular regions between ends of the non-reset zone and 45 to 95% of a maximum possible number of steering wheel revolutions in a clockwise and a counterclockwise direction; and defining the boundary zone as angular regions between 45 to 95% and 100% of a maximum possible number of steering wheel revolutions in the clockwise and the counterclockwise direction.
 11. The method of operating a steering unit for a steer-by-wire ship control system according to claim 9, further comprising the steps of: depending on a speed of the ship, if no auto-pilot device is activated, increasing the mechanical resistance generated at the steering wheel up a predetermined threshold value, and the mechanical resistance being generated at the steering wheel by the device for generating mechanical resistance during an actuating of the steering wheel by the operator in either the reset zone and the non reset-zone; and maintaining the mechanical resistance at a constant predetermined value at every speed of the ship, if an auto-pilot device is activated, and in the boundary zone, the mechanical resistance is either at a constant maximum value or is increase up to the maximum value, depending on a number of revolutions to go before achieving the maximum possible number of steering wheel revolutions.
 12. The method of operating a steering unit for a steer-by-wire ship control system according to claim 11, further comprising the steps of: defining a speed, below which no mechanical resistance is generated by movement of the steering wheel and, above this speed, the mechanical resistance is increased up to a predetermined threshold value, as a function of the speed, if no auto-pilot device is activated, and the angular position of the steering wheel is within either the reset zone or the non-reset zone. 